2011 年 34 巻 7 号 p. 1005-1010
Our previous studies have demonstrated that lipid peroxidation in the lenses of hereditary cataract model rats (Ihara cataract rat (ICR)/f rats) caused a dysfunction in Ca2+ regulation. In the present study, we investigated the effect of in vitro hydrogen peroxide (H2O2) stimulation on lipid peroxide (LPO) and the activities of sarco-/endoplasmic reticulum and plasma membrane Ca2+-ATPase (SERCA and PMCA) in the ICR/f rat lenses. An increase in LPO level and decreases in the SERCA and PMCA activities were observed with increasing H2O2 concentration, and pretreatment with diethyldithiocarbamate, a potent radical scavenger, attenuated these changes in normal and ICR/f rat lenses. The glutathione levels, glutathione peroxidase and glutathione reductase activities are significantly lower in ICR/f rat lenses than in normal rat lenses. Furthermore, we presented as two kinetic parameters such as DP (defense point) and Ks (reactive constant) analyzed from above various biological responses vs. H2O2 concentration–profile curves using a one-exponential equation. The DPs for LPO, SERCA and PMCA in ICR/f rat lenses is lower than in normal rat lenses. In contrast to the results in DP, the Ks for LPO, SERCA and PMCA in ICR/f rat lenses is higher than in normal rat lenses. In addition, the closed relationship of was observed between DP and Ks for LPO, SERCA and PMCA. These results show that the resistance to H2O2 in the ICR/f rat lenses is lower than that of normal rats. The DP and Ks values can provide an useful information for resistances to various stimuli in cells and tissues.